Incandescent electric lamp.



No. 876,390. PATENTED JAN. 14, 1908. H. C. PARKER & W. G. CLARK.INGANDESGENT ELECTRIC LAMP.

APPLIUATION FILED JAN. 24, 1906.

VENTORJ' WITNESSES: g 2

BY [ham/Q1.

incandesrent electric UNITED STATES PATENT OFFICE.

RSFIIEL (f. PARKER AND WALTER G. OLA RK,

OF NEW YORK, N. Y., ASSIGNORS TO PARKER- (LARK ELECTRIC COMPANY, OFJERSEY CITY, NEW JERSEY, A CORPORATION OF NEW ERSEY.

INCANDESCENT ELECTRIC LAMP.

Specification of Letters Patent.

Patented Jan. 14:, 1908.

Application filed January 24.1906. Serial N0.'297.540.

To all whmn, it may concern:

Be it known that we, IIEasonEL C. KER, of New York, countyof Kings, andState of New York, and WALTER G. CLARK, of the 5 city, county, and Stateof New York, have invented a new and Improved Incandescent Electriclamp, of which the following is a full, clear, and exact description.

()ur invention relates to improvements in lamps and particularly tocontacts therefor, and more especially to improvements in the contactsfor that class of incainlescent electric lamp in which a quartzor otherrefractory tube is provided 15 with a refractory conductive film orlining.

lamps of this kind are sometimes made hollow and are sometimes providedwith a non.- conducting core or filler. In either case it is thepractice to fill the ends of the tube or other hollow structure with agood conductor into which the leading-in wires extend. The dillicultywith this arrangement is that the current follows the good conductorfreely to the point of where it meets the core, or if the member ishollow, where it meets the sustaining plug, and here the current issuddenly de- Ilected almost as a whole to the conducting refractorylining and the strain caused by the concentrated impact of current andthe sharp temperature variations at a single point is apt to break orseriously strain the tube, filament or lining. We have found that bygraduating the better conductor at the end portions'of the tube orhollow member, makingthe inner portion comparatively high resistant, andthe outer portion low resistant, that the current is taken up through acomparatively extended length of the refractory lining and so a contactis made which is perfoot and which does not unduly strain the hollowmember. \Ve have applied this in vention to lamps as stated anddoubtless a contact may be made in a similar way with other conductors.

With these ends in view our invention consists of the combination with arefractory conductor of a better conductor lying against and making aside contact with said refractory conductor, and connecting with theleading-inwire and of graduated resistance, which arrangement will behereinafter described in detail and claimed.

Reference is to be had to the accompanying drawings forming a part ofthis specification, in which similar letters and figures of PAR-reference indicate corresponding parts in all the views.

Figure 1 is a side elevation with the end portions in section, of a lamshowing our improvements; Fig. 2 is a sire elevation with one endportion in section, showing a modification of the invention, and Fig. 3is a view similar to Fig. 2, but showiiur another slight modification orvariation.

, In Fig. 1 is shown the more common form of lamp of the kind mentionedin which a tube 10 of highly refractory material is provided with arefractory conductive lining .11, and with a non-conducting core orpackin 12, which fills the body portion of the tu e to a point near theends. As shown in this figure, the hollow member 10 is in the form of astraight tube and electrical connections are made by means of aconductor 13, 13, filling the end portions of the tube and into whichthe leading-in wires -1 4 extend. It has been the practice to fill theend portions of the tube with graphite or some good conductor, extendthe leading-in wires into the said conductor, then pack the ends withasbestos or some poor conductor of heat and seal the ends. The asbestosor. other packing and the seal can be used with our invention, but we donot show it here, as it is immaterial.

\Vith the good conductor or one of a uniform resistance it will bereadily seen that the current will leave the said conductor at the pointwhere it meets the non-conducting core 12 or the plug 15, shown in Figs.2 and 3, in which case the strain, both by reason of current impact andtemperature change, is opposite the said meeting point of the two parts,To overcome this we make the conductor 18 comparatively high resistantat its inner end where it meets the core 12 or plug 15 and comparativelylow resistant at the outer end as shown at 13; This can be easily doneby mixing a good conductor, such as graphite, with any powdered poorconductor, such for instance, as quartz, carborundum things and having arelatively large proportion of the poor conductor at the inner part ofthe conducting portion or member. The drawing shows the graduation, butin actual practice, as it would be diflicult to graduate a completemass, the parts 13, 13 may be obtained by leaving the member 10 straighti resisting qualities of the conductor where it made in a series ofstrata with the innerstratum relatively high resistant and the outerstratum relatively low resistant, while the intermediate strata may beoorrespondingly graduated, and the effect is exactly as shown in thedrawing, and it will be seen that the current will leave the parts 13,13 at all points between the inner'and outer ends of said member and sono serious strain results at anyone point.

Obviouslythe shape of the hollow member 10 can be changed infinitelywithout affecting the invention. To illustrate this we show in Fig. 2,the member 10 left hollow throu 11 its body portion and constrictedslight y so that the end'parts 10 are larger and the plug 15 is placedat the point of constriction and the conducting member consisting of theportions 13, 13 inserted as already described. In Fig. 3, a like effectis on the outside but expanding it at the ends as shown at 10". Theseseveral modifications show that still others may be made and that theessential thing is to graduate the meets the relatively refractory andhigher resisting conducting lining 11 or its equivalent.

Having thus fully described our invention, We claim as new and desire tosecure by Letters Patent,

1. The combination with a relatively high resistance electricalconductor, of a con tacting ,member lying against and making a sidecontact-with the said conductor, the said contacting member 'beinggraduated from a higher to lower resistance from one end portion to theother.

2. The combination with a hollow member having a refractory conductivelining, of a contact member filling the end portions of the said hollowmember, the contacting member being of gradually varying resistance andcontacting along its sides with said conductive lining.

3. The combinationwithahollow member having a refractory conductivelining, of a contact portion forming a closure in the end of the saidhollow member, the said contact portion being relatively high resistantat its inner end and relatively low resistant at its outer end andcontacting along its sides with the conductive lining.

4. The combination with a refractory conductor, of contacts at the endportions of and making a side contact with the conductor, the saidcontacts being adapted to connect with a source of electrical supply andgradually increasing in resistance from their outer to their innerportions.

5. The combination with a hollow member having a refractory conductivelining, of a contact portion of gradually varying resistance filling theend portions of said hollow member, and making contact along the sidesof said contact member and conductor and means "for limiting the inwardextension of the said contacting portion.

6. The combination with an electric conductor, of a contact portionlying against,

and making a side contact with the said conductor, the said contactportion being at one end of a resistance approximating that of the saidconductor and at the other end of a higher resistance.

7. The combination with the non conducting tube, expanded at the ends,and having a refractory conducting lining, of a contact conductorfillingthe said expanded ends and havin a higher resistance at one end than attli e other,

HERSOHEL C; PARKER. WALTER G. CLARK.

Witnesses:

WARREN B. HUTcHINsoN, WILLIS A. BARNES.

